Don,
As far as a replacement for your sheared off screw, you can get two replacement screws at Langs Old Car Parts (www.modeltford.com). Their part number is 5023-4-5. I know these are for a Ford Model T, but they are exact replacements and work fine. My 1930 starters (I have two) do not have the two shims that you show in the picture.
Regards,
Bill Jewell